A great many dobbies are previously known. The dobby can serve as a module in the weaving machine and individual weaving machines can be provided with different types of dobbies. For example U.S. Pat. No. 5,309,949, it is previously known to use of lifters and knives in order to control the movements of the treadles in a dobby. The prior art uses a knife arrangement which is mounted in a stand, in which rotatable drums are arranged. The knives are provided with pins at their ends, which are guided in grooves on the drums so that, during the coordinated rotation of the drums, the knives are imparted movements away from and towards one another. Lifters or rocker members are designed to interact with the knives so that a respective lifter can interact alternatively with the respective knife to bring about different shed positions for the heald frames of the weaving machine.